1. Field of the Invention
The present invention relates to a system or kit for disinfecting contact lenses, and to a method of disinfecting contact lenses utilizing that kit or system. More particularly, this invention relates to a two part, hydrogen peroxide based system for disinfecting contact lenses.
2. Discussion of Related Art
Hydrogen peroxide is becoming recognized as a safe and efficacious disinfectant for contact lenses. In this regard there is unaminity between the clinicians responsible for designating such systems and the users of such products. This acceptance is primarily attributable to the fact that such systems are substantially predictable in their intended use, taking into consideration the wide range of individuals who rely upon the disinfecting effect and the good and bad habits of those individuals. However, after disinfecting, residual hydrogen peroxide must be removed before again wearing the lens. This is because hydrogen peroxide, even in trace amounts, can cause corneal irritation in sensitive individuals. It is in this respect that prior art systems fail, or introduce complications resulting in user errors, elevated costs, and unpredictability. For example, repeated rinsing to remove residual hydrogen peroxide in isotonic, buffered saline solution is effective only if repeated extractions over a longer period are made. The resulting inconvenience motivates the user to take short cuts or otherwise deviate from recommended procedure with attendant risk of imperfect removal of residual hydrogen peroxide or introduction of microorganisms. Other systems rely on enzymatic or inorganic catalysis to decompose residual hydrogen peroxide. Such systems are, when looking at the average user, problematic and slow.
The following publications provide further background concerning the use of hydrogen peroxide to disinfect contact lenses: Gasset et al., "Hydrogen Peroxide Sterilization of Hydrophilic Contact Lenses," Archives of Ophthalmology, Vol. 93, pages 412-415 (1975); U.S. Pat. No. 3,912,451 issued to Gaglia; and U.S. Pat. No. 4,521,375 issued to Houlsby. These publications relate to three different means for solving the same problem; namely, how to effectively neutralize the hydrogen peroxide which remains in and on a contact lens after treatment with that compound. The solutions discussed in these publications are based on the use of sodium thiosulfate (Gasset et al.), a platinum catalyst (Gaglia), and sodium pyruvate (Houlsby) to neutralize hydrogen peroxide. These systems also suffer from various problems, such as instability, unpredictability and slowness.
The present invention employs as a means to destroy residual hydrogen peroxide the well known reducing agent sodium thiosulfate. The article by Gasset et al., discloses a system which utilizes sodium thiosulfate for the same purpose, but practical difficulties relating to stability, predictability and rate of reaction have prevented the adoption of that system. The present invention provides unexpected solutions to the above-discussed prior art problems, and presents other unexpectted advantages as well.